 Hello friends, let me introduce myself first, myself Mr. S. K. Kulkarni, Assistant Professor, Civil Engineering Department, Balchen Institute of Technology, Shalapur. Topic of our today's discussion is method of finding missing entries in a page of a label book by Rise and Fall method. Learning outcome of today's session, at the end of this session students will be able to evaluate missing entries in a label book page by using Rise and Fall method. Introduction. What happens friends, sometimes some entries in a label book page may not be visible or readable clearly. So we have to find these missing entries from other available readings. That is why we are studying this particular topic. Now what is Rise and Fall in ground? Here you can see the ground is continuously rising or falling in this fashion. Here first three staff readings, they are on continuously rising ground. Then there is a fall and again there is a rise. So here there is a level or dumpy level which is being used for taking levels of different points. What will happen? When fall is there, part of the staff will go down. More part of the staff will go below and the reading will increase on the staff. Hence there is rise in ground, the reading on staff will decrease automatically because staff will be coming up. So that is the important thing which is to be kept in mind. When fall is there, reading will be more. When rise is there, reading will be less. Now let us see one exercise which will make the things more clear to us. Here some missing entries are there in this particular level book page. And we have to find these missing entries and also the levels of all points. So here see x1, backside reading is missing. Then this x2 is missing. Then x3, this foresight reading is missing. x4, this RL is missing. x5, this RL is missing. And x6, this remark is missing. So these missing values we have to find by rise and fall method. Fall is given. There is no rise because ground is continuously falling that means. Now how to find these missing entries in such cases? So in rise and fall method we know what is that every present reading is compared with the next reading. That means backside reading x1 must be compared with the next reading that is intermediate side reading of 1.525. And it is given that there is fall of 0.675 in these two readings. When there is fall we know next reading will be more than the previous reading because fall means there is increase in reading. Just now we have discussed. That means difference of these two readings must be 0.675 and x1 must be smaller than the intermediate side reading. This backside must be smaller. So let us find out what is x1 from this. Yes here see increase in reading means there is falling ground and decrease in reading means there is rise in ground. This we know. Now equation number one RL of next point is equal to RL of previous point plus rise. This is important equation which we know. And RL of next point in case of fall it is equal to RL of previous point minus fall. That means if rise is there you have to add it in the RL of previous point to get RL of next point. And if there is fall it is to be deducted from the RL of previous point. These two equations are important. And now let us compare backside and subsequent IS reading intermediate side reading x1 and 1.525 these two readings. Difference between those two readings is 0.675. So and one more thing is that the x1 that is backside reading is smaller because now there is fall in ground. So next reading is higher. So this will be equation 1.525 minus x1 must be equal to 0.675. Therefore x1 is equal to 0.850 after solving this we get x1 equal to 0.850. So it is entered here. We have got one missing value in the form of x1 equal to 0.850. Now next missing value which we can find easily that we should consider. Now x4 one can find easily from these two readings remember RL of previous point that is benchmark is known. Fall is given then RL of next point can be easily found. How RL of previous point minus fall will give you RL of this particular next point that is x4. It is a fall so it is to be deducted minus. So this will be the equation 105 minus 0.675 will be equal to 104.325. This will be the RL of RL in the place of x4 station number 2. Now which next reading we can find? Here we can see backside reading and foreside reading both are written in the same row. What this indicates? This indicates that there must be change point here because at change point we know there are two readings taken on the same staff. So they are written in the same position one in from the previous instrument position and one or next in the from the new instrument position. So here there must be a remark in the form of x6 equal to change point x6 is a missing remark. So change point must be written in place of x6. So this also we have got. Now next x2 x2 is missing x2 is to be found now compare base backside reading x2 with next intermediate site 1.2500. In these two readings there is a fall of 0.350 it is given. So x2 and 1.250 their difference must be equal to 0.350 and which will be the larger value. Naturally this there is a fall so this is the larger value. So 1.250 minus x2 must be equal to 0.350 this will be the equation. So here x2 is equal to 0.900. So enter the value of x2 0.90 in this fashion. Now which is the next unknown value we can see here x5 is next unknown. So one can easily find x5 from these two values RL of previous station and fall in ground is given. So 103.050 minus 0.605 must be equal to x5 RL of next point. So come on let us do this calculation. So what we get x5 is equal to 102.445. So enter it here x5 is 102.445. Now one more missing reading is there x3 that is 4 site reading. And for finding this what we should do we should compare now this 4 site reading with previous reading intermediate side reading is 1.855. So when compare when we compare these two difference between these two amounts to be 1.130 it is given fall is 1.130. So their difference is 1.130 and naturally x3 must be the value which will be more because there is fall and this intermediate site reading will be lesser. So what will be the equation x3 minus 1.85 must be equal to 1.130. So let us see what we get x3 now yes x3 is equal to 2.985. So enter the value of x3 here 2.985 and we have got all the missing entries. Now take the summation of all sigma back side sigma 4 side then summation of rise minus summation of fall and last rl minus first rl. This is arithmetic check we know in case of rise and fall method check whether it is matching these values are given to us in the table. Now these are the calculations now friends we will pause a little here there are two questions for you solve them and you can solve them easily. First question is when there is fall in ground next level reading of station will increase oblique decrease in comparison with previous level reading. You have to select the correct word here increase or decrease and second question is how is arithmetic checked okay friends solve these two questions. So what are the answers when there is fall in ground next there will be increase in comparison with previous level reading right and what is the arithmetic check sigma back side minus sigma 4 side is equal to sigma rise minus sigma fall is equal to last rl minus first rl and substituting values in this we get our check satisfied right there is no need of any revision in the calculations these are the references for today's session thank you